Electron gun with connector of alternate electrodes shielding intermediate electrode

ABSTRACT

A substantially U-shaped electrical wire configuration intercoupling the pair of second anodes in a cathode-ray kinescope electron gun assembly for preventing arcing and reducing electron beam drift in the presence of high-potential electric fields.

Unite States atent [72] Inventors Filed Patented Assignee App]. No.

John McQueen Leonard D. Minutillo, Sayreville, both of NJ.

Mar. 28, 1969 Nov. 9, 1971 Griffiths Electronics Inc.

Linden, NJ.

ELECTRON GUN WITH CONNECTOR OF ALTERNATE ELECTRODES SHIELDING INTERMEDIATE ELECTRODE 3 Claims, 6 Drawing Figs. [52] US. Cl 313/82, 313/292 [51] Int. Cl ..I-I01j 29/02, H01j 19/42,I-I0lj 29/46 [50] Field of Search 313/82, 70 C, 69 C Zia 5 Primary Examiner-Robert Segal Attorney-Ostrolenk, Faber, Gerb & Sofien ABSTRACT: A substantially U-shaped electrical wire configuration intercoupling the pair of second anodes in a cathode-ray kinescope electron arcing and reducing electron gun assembly for preventing beam drift in the presence of high-potential electric fields.

ELECTRON GUN WITH CONNECTOR F ALTERNATE ELECTRODES SIIIELDING INTERMEDIATE ELECTRODE This invention relates to cathode-ray tube kinescopes, in general, and to a simplified electrical connection for the electron gun thereof, in particular.

In cathode-ray kinescopes of the tricolor variety, it is not uncommon for the potential applied to the second anode to be some -25 kilovolts or so greater than the potential applied to the focusing electrode. In addition, there is developed within the neck of the kinescope an electrostatic field having a value comparable to the potential applied to the second anode, due to the buildup of electrostatic charge as the tube is operated in a television receiver. This electrostatic field tends to upset the convergence established within the picture tube and, in some instances, to cause arcing with the relatively low voltage focusing electrode.

It has been found that some of these problems can be reduced by constructing the electron gun assembly to provide in essence a pair of second anodes, each of which is positioned on one side of the focusing electrode. A plurality of electrically conducting jumper wires have then been employed to maintain these two second anodes at the same kilovolt potential, and have been found to reduce the effects of arcing and the drift of the electron beam caused by the electrostatic field.

In one configuration of an electron gun assembly for a tricolor kinescope, the following arrangement of jumper wires was found to have a pronounced effect in reducing those phenomena. Three spaced, parallel jumper wires were used to connect the pair of anodes for two of the three electron gun assemblies, while a pair of spaced, parallel jumper wires were employed to connect the pair of second anodes for the third electron gun assembly. The use of a third jumper wire was precluded in this last instance as it was found to physically interfere with the electrical connection serving to provide the relatively low potential to the focusing electrode of the assembly.

It will be noted, however, that a pair of welds (or similar mechanical connections) are needed in this electron gun configuration to connect each jumper wire between its pair of associated second anodes. Such an arrangement is undesirable in a manufacturing process since, for the eight-jumper-wire configuration just described, 16 welds would be necessary for just this structure alone.

It is an object of the present invention, therefore, to provide a modified connection between the second anodes of such an electron gun assembly which would limit the required number of welds.

It is a further object of the invention to provide such a connection which at the same time does not deleteriously affect the performance previously provided.

As will become clear hereinafter such a modified connection includes constructing the spaced, parallel jumper wires in at least one substantially U-shaped configuration. The base of the U-shaped arrangement is provided to be in electrical connection with one of the pair of second anodes while the legs of the U-shaped construction provide the proper electrostatic field to minimize electron beam drift and connect the other pair of such anodes.

In that type of electron gun assembly where heretofore three jumper wires were employed, the modification according to the present invention comprises arranging a pair of such U-shaped members effectively in series and in oppositely facing directions to provide what appears as an S-shaped configuration. The free ends of the outer leg sections are electrically and mechanically connected to alternate ones of the pair of second anodes while the two base or curvature portions of the S" configuration overlie the respective anodes. In this arrangement, therefore, it will be seen that the six welds heretofore employed are replaced by only a pair of welds, thus saving a number of steps in the fabrication of this jumper connection.

In that type of arrangement where a pair of jumper wires were employed to effect the electrical connection, the modification according to the present invention comprises arranging the legs of the U configuration to be electrically and mechanically connected to one of the second anodes and arranging the base or curvature portion to be electrically and mechanically connected to the other second anode. In this arrangement, the previously employed four welds are replaced by three such connections.

It will thus be seen that a tricolor kinescope employing two of the S-shaped configurations and one of the U-shaped configurations will require a total of seven welds instead of the 16 welds required with the previously employed eight-jumperwire arrangement. This represents a substantial simplification of the electron gun fabrication.

These and other objects of the present invention will be more clearly understood from a consideration of the following description taken in connection with the drawings in which:

FIG. 1 represents a simplified view of an electron gun assembly for use in a cathode-ray kinescope showing the employment of three jumper wires connecting one second anode to another second anode, the two being separated by a focusing electrode;

FIG. 2 is a view of that electron gun assembly of a kinescope in which a pair of jumper wires is employed for connecting the two second anodes, with the electrical connection to the focusing electrode between the second anodes also being shown;

FIG. 3 shows a jumper-wire assembly constructed in accordance with the present invention for use in place of the three-jumper-wire assembly show in FIG. 1;

FIG. 4 is a second jumper-wire arrangement in accordance with the invention for use in place of the two-jumper-wire assembly shown in FIG. 2; and

FIGS. 5a and 5b are views showing the planar relationship between the jumper wires of FIGS. I and 2 and of FIGS. 3 and 4 with respect to the various elements of the electron gun assembly.

Referring now to FIG. 1, there is shown in representational form a portion of an electron gun assembly employed in a cathode-ray picture tube. The cylindrical portion 10 represents one of a pair of second anodes of such an electron gun assembly (grid number 3) and typically has applied to it a potential of approximately 20-25 kilovolts. The other of the pair of second anodes 11 (grid number 5) is also shown and is electrically connected to the anode 10 by means of a plurality of spaced, parallel jumper wires I2, 13, and I4. interspersed between and aligned with the second anodes I0 and 11 is a focusing electrode 15 to which is typically applied a potential of approximately 400 volts.- A pair of elongated, multiform glass support members 16 and 17 are shown, and are used to exactly position and align the second anodes l0 and II and the focusing electrode 15 within the electron gun assembly. This securement is made during the fabrication of the electron gun assembly, with the focusing electrode 15 and the second anodes l0 and II being embedded in the molton glass member when that member is in its molten state prior to compressive forces being applied thereto to urge the supporting portions of the electrodes into the insulating members 16 and 17.

As is known, the jumper wires l2, l3 l4 serve to reduce the effect of electrostatic fields present within the neck of a tricolor kinescope. When these jumper wires are not provided, it has been found that this electrostatic field (having a potential comparable to the second anode kilovolt potential) caused arcing to the low-voltage focusing electrode, as well as preventing the effective convergence of the associated electron beams.

As indicated in FIG. 1, these jumper wires I2, 13 and 14 are each secured to the pair of second anodes 10 and 11 by means of a plurality of mechanical connections, such as welds. Thus, for the arrangement shown in FIG. 1, six such welds W W are shown. In the fabrication of the electron gun assembly, a certain amount of time is required to perform the welding operation.

In FIG. 2 there is shown a second electron gun assembly employing spaced, parallel jumper wires, but in a physical location where the focusing electrode 15 is provided with its relatively low direct potential by means of a wire connector 20. Here, to prevent interference with this wire connector 20, only a pair of jumper wires 22 and 23 are employed. These wires again require two welds for each, yielding a total of four welds for the assembly.

The three-jumper-wire arrangement of FIG. 1 may be employed for one electron gun of a tricolor kinescope while the two-jumper-wire arrangement of FIG. 2 may be used for a second such electron gun. A third electron gun exists in the tricolor picture tube, and an arrangement of jumper wires as employed in FIG. 1 may be used for this third electron gun, to prevent the arcing and misconvergence previously described. That arrangement then, also requires six welds for connection of the three jumper wires.

The sum total of the welds needed in order to prevent arcing and misconvergence therefore is 16 welds. As will be appreciated, the time and expense in making these welds is an element of cost which it would be desirable to eliminate or at least minimize.

Referring now to FIG. 3, there is shown a jumper-wire assembly constructed in accordance with the present invention, and intended as a substitute for the three-wire arrangement of FIG. 1. As shown in this drawing, a single jumper wire 29 is shown but is fabricated as a pair of series-connected, oppositely facing U-shaped configurations, to provide the same effect as the three-jumper-wire arrangement of the previous drawing. The ends of the single jumper wire 30 and 31 are shown electrically and mechanically connected, as by a pair of welds, to the second anodes l and 11. The bends and fabrication of the jumper wire 29 is such that electrical connection may be made by means of wire portions 29a, 29b and 29:: between the second anode I0 and the second anode 11. In an alternative embodiment, the curvature portions may only overlie, instead of electrically contact the second anodes l0 and 11. It will be seen that this essentially S-shaped arrangement produces the same electrostatic field as is provided by the arrangement of FIG. 1 but requires only one third (two as against six) the number of mechanical connections (i.e. welds) there shown. Thus, a significant reduction in the number of welds necessary for this arrangement (as well as for the second three-jumperwire arrangement of the electron gun assembly) results.

Referring now to FIG. 4, there is shown a jumper-wire assembly according to the invention which is intended as a substitute for the two-jumper-wire arrangement of FIG. 2. Here a single wire 39 is employed, and fabricated in a substantially U- shaped configuration. The legs 40 and 41 of the U-shaped wire are electrically and mechanically connected to the second anode 11 by a pair of welds (W,, W,) while the base or curvature portion 42 formed by the wires 40 and 41 is electrically and mechanically connected to the second anode by means of a third weld (W Again the function served by the spaced, parallel jumper wires in FIG. 2 are served by the configuration of FIG. 4, but it will be noted that the FIG. 4 arrangement employs one less weld (three as against four).

It will be noted, therefore, that the fabrication of a single wire into a U-shaped configuration as in FIG. 4 and into a pair of U-shaped integrally joined configurations series-connected to form an S-shaped configuration as in FIG. 3, reduces the total number of welds needed to fabricate the jumper-wire-as' semblies employed in the prior art high-voltage tricolor kinescope. More particularly, it will be noted that the previously required 16 welds are herein replaced by seven such welds.

FIGS. 5a and 5b illustrate the different planar relationships between the jumper-wire assemblies of FIGS. 1 and 2 and of FIGS. 3 and 4, respectively. In particular, it will be noted that the plane of the jumper-wire connectors is offset with respect to the planes of the other elements of the electron gun assembly. However, this offset is not critical, the exact amount being dependent upon the degree of electric field isolation desired. A typical value for present-day color television picture tubes may be about one quarter of an inch.

Thus, by reducing the number of mechanical connections while not impairing the electrical performance provided, the arrangements of the invention offer a significant advantage in the construction of electron gun assemblies. As will be appreciated, a major cost in electron gun assemblies is entailed not only with the materials needed in forming the various components but in the times and portions necessary in order to fabricate the assemblies. By reducing the number of welding steps from 16 to seven and number of parts handled, in accordance with the present invention, the overall cost of the assembly is substantially diminished. Although this reduction may amount only to l or I cents per unit, it will be appreciated that this represents a substantial savings in present color television technologies where over 6 million tubes each year are fabricated and sold. Many hundreds of thousands of other tubes are manufactured but never get into production because of one defect or another, and the cost saving exists there too.

Thus, while the present invention may save what might appear to be only a trifling amount in the way of the overall cost of a color television picture tube or color television receiver, it will be appreciated that in a market numbering upwards of 7 million color picture tubes, a lor 2-cent cost reduction per tube would amount to a considerable cumulative saving. The present invention is operative to effect such an overall savings in a manner which in no way impairs the electrical performance provided. Thus, through the simple expedient of employing a single, somewhat longer jumper wire and arranging it in a plurality of bends to form either a U-shaped or S- shaped arrangement, a significant cost reduction can be effected.

The embodiments of the invention in which an exclusive privilege or property is claimed are defined as follows 1. In an electron gun assembly of the type having axially aligned electrodes including an electron-emitting cathode, a control grid, a first anode, a pair of second anodes, and a focusing electrode interspersed between said pair of second anodes and intended for use in a cathode-ray kinescope, and wherein the direct voltage difference between the operating potentials applied to said second anodes and to said focusing electrode is of the order of kilovolts, the improvement comprising:

an elongated electrical conductor having first and second bent portions so as to form three spaced substantially parallel arms aligned substantially parallel to the longitudinal axis of the assembly, said electrical conductor being electrically isolated from said focusing electrode while electrically connecting said pair of second anodes to maintain the second anodes at a single potential level and to effectively shield said focusing electrode from any stray electrostatic fields present within said kinescope and having a tendency to defocus and displace an electron beam directed therethrough;

each free end of said electrical conductor being mechanically and electrically connected to an associated one of said pair of second anodes;

the bent portions of said electrical conductor engaging associated ones of said pair of second anodes wherein said elongated conductor forms an electrostatic shield about a portion of the focusing electrode to shield the focusing electrode from extraneous electrical fields while reducing the number of weldments otherwise required to secure shield members to the second anodes.

2. The device as described in claim 1 wherein the intermediate portions of the arms of said electrical conductor which provide the effective shield for said focusing electrode lie in an imaginary plane which is laterally spaced from the outer surfaces of said pair of second anodes.

3. The device as described in claim I wherein the intermediate portions of the arms of said electrical conductor which provide the effective shield for said focusing electrode lie in an imaginary plane which is laterally spaced from the outer surfaces of said pair of second anodes. 

1. In an electron gun assembly of the type having axially aligned electrodes including an electron-emitting cathode, a control grid, a first anode, a pair of second anodes, and a focusing electrode interspersed between said pair of second anodes and intended for use in a cathode-ray kinescope, and wherein the direct voltage difference between the operating potentials applied to said second anodes and to said focusing electrode is of the order of kilovolts, the improvement comprising: an elongated electrical conductor having first and second Bent portions so as to form three spaced substantially parallel arms aligned substantially parallel to the longitudinal axis of the assembly, said electrical conductor being electrically isolated from said focusing electrode while electrically connecting said pair of second anodes to maintain the second anodes at a single potential level and to effectively shield said focusing electrode from any stray electrostatic fields present within said kinescope and having a tendency to defocus and displace an electron beam directed therethrough; each free end of said electrical conductor being mechanically and electrically connected to an associated one of said pair of second anodes; the bent portions of said electrical conductor engaging associated ones of said pair of second anodes wherein said elongated conductor forms an electrostatic shield about a portion of the focusing electrode to shield the focusing electrode from extraneous electrical fields while reducing the number of weldments otherwise required to secure shield members to the second anodes.
 2. The device as described in claim 1 wherein the intermediate portions of the arms of said electrical conductor which provide the effective shield for said focusing electrode lie in an imaginary plane which is laterally spaced from the outer surfaces of said pair of second anodes.
 3. The device as described in claim 1 wherein the intermediate portions of the arms of said electrical conductor which provide the effective shield for said focusing electrode lie in an imaginary plane which is laterally spaced from the outer surfaces of said pair of second anodes. 